(中南大學 材料科學與工程學院，長沙 410083)
摘 要: 采用硬度測試、電導率測試及透射電鏡觀察，研究固溶后降溫至440 ℃預析出處理時間對7A55鋁合金板材力學和腐蝕性能的影響。結果表明：隨預析出處理時間的延長，基體析出相逐漸增多且長大，導致合金時效后硬度和強度先提高而后降低；晶界析出相逐漸長大，晶界無沉淀析出帶寬化，晶界相不連續(xù)性先提高而后降低，導致合金抗晶間腐蝕和剝落腐蝕性能也先升高而后降低。
關鍵字: 7A55鋁合金；預析出；晶間腐蝕；剝落腐蝕
（School of Materials Science and Engineering, Central South University,Changsha 410083, China）
Abstract:The influence of pre-precipitation at 440 ℃ after solution on the mechanical properties and corrosion resistance of aluminium alloy 7A55 was investigated by hardness tests, conductivity tests and transmission electron microscopy (TEM). The results show that with increasing the pre-precipitation time, the density of the precipitates in the matrix becomes higher and then the size becomes larger. As a result the hardness and strength increase first and then decrease. At the same time, the particles at the grain boundaries become larger with wider precipitate free zone, and the discontinuity of these particles increases first and then decreases with increasing pre-precipitation time. Consequently, intergranular corrosion and exfoliation corrosion resistance increase first and then decrease.
Key words: 7A55 aluminium alloy; pre-precipitation; intergranular corrosion; exfoliation corrosion
